Cowlitz River

Catchment area of ​​the Cowlitz River

The Cowlitz River is a 170 km long tributary of the Columbia River in the U.S. state of Washington. With its tributaries of the Cowlitz River the largest part of Mount Rainier, Mount Adams and Mount St. Helens drained. Its catchment area is located in Lewis County between the Cascade Range and the citys Kelso and Longview. It covers 6400 square kilometers.

The most important tributaries of the Cowlitz River and Toutle Rivers are Cispus River. The latter St. Helens in 1980, blocked by lahars during the eruption of Mount.

Bridges

The Cowlitz River is spanned by several bridges. Directly above the confluence with the Columbia River connecting a railway bridge the Port of Longview with the railway line of the Burlington Northern and Santa Fe Railway ( BNSF ), a road bridge located next to it. A little higher connect two bridges with the rest of West Kelso Kelso and north of Kelso crosses a railway bridge for the Columbia and Cowlitz Railway the river.

In a two-lane bridge connects Lexington SR 411 with the ramp 42 of Interstate 5 on the east bank. In Castle Rock a bridge from the city center to school and living quarters on the other side of the river and a few miles continues, just above the confluence of the Toutle River crosses the BNSF rail line the river. Between Vader in Lewis County and Toledo in Cowlitz County Interstate 5 over the river and at Toledo crosses the SR -505 the waters.

The U.S. Highway 12 leads west of Mossyrock on the Mayfield Lake. From both sides of a roadway in the direction of the opposite shore was built, which is connected in the middle by a bridge section. At the dam a small bridge on the SR 122 connects both banks. To the east of Mossyrock the Cowlitz River Bridge was until 1971 with a length of 168 m, the longest arch bridge made ​​of concrete in North America.

At the top of the reefs Lakes a road bridge connecting the forests south of the river with Morton and Glenoma on the north side. In Randle the river crosses the SR 131 and thus opening up the area on Cispus River and the northern areas of the Mount St. Helens National Volcanic Monument. U.S. Highway 12 crosses the river again in Cora and then in the Big Bottom Valley between Randle and Packwood. Above Packwood cross numerous forest paths, the headwaters of the Cowlitz River.

Reservoirs

On the Cowlitz River there are three major dams with hydroelectric plants and a number of smaller power plants.

The Cowlitz Falls Project is a 70 - megawatt power plant, which was built in the early 1990s and completed in 1994. The dam is almost 43 meters high and 213.5 long. The power plant generates 260 gigawatt hours of electricity annually. The reservoir is located below Randle at the mouth of Cispus Rivers.

On Mossyrock Dam electricity for Tacoma City Light began in 1968. The dam has a height of 184.5 m and accumulates the 37 km long Lake reefs on. This was formerly known as Davisson reservoir. The building is the highest dam in the Pacific Northwest. The dam is named after the nearby town of Mossyrock in the neighborhood and the lake bears the name of the place reefs, which has gone together with the cosmos during the flooding of the reservoir.

The Mayfield Dam is 259 m long and 56 m high. A 262 m long tunnel connects the reservoir to the turbine house. Here, the power generation began in 1963. Mayfield Lake offers numerous recreational opportunities, as several parking facilities are located on its banks and is a few kilometers below Mossyrock due to its location attractive. The regulated inflow from the reefs Lake leaves the water level of the Mayfield Lakes fluctuate very low.

Packwood Lake was created in 1964 by a dam of the Washington Public Power Supply System (now Energy Northwest ). The main purpose of the dam is to retain the water of a lake formed by a landslide. He also leads water from a hydroelectric power station with a capacity of 27 megawatts, which is located 300 meters below the valley of the Cowlitz River at Packwood. In the planning and construction of the dam, it was kept that by building the wildlife took no damage in the area. The water level was raised only a few feet through the dam.

A serious side effect of the eruption of Mount St. Helens is the transport of huge amounts of sedimentary by the North Fork Toutle River. After the eruption of the content of sediments had risen to 5,000 times in the river, causing the Toutle River was one of the most saturated with sediment rivers in the world. The Toutle River Sediment Retention Structure was built to hold back the sediments before they are washed downstream and clog the riverbed. This flooding would be strengthened along the lower reaches and the fairway of the Columbia River are increasingly shallower. This must be dredged regularly anyway.

Hydrology

The United States Geological Survey maintains a level in Castle Rock. The annual average discharge amount, on average, from 1928 to 2005 was 259 m³ / s The highest value recorded was 3944 m³ / s on 23 December 1933, the lowest flow rate of 28 m³ / s was measured on November 7 and 8, 1935.

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